A high-order nonlinear compensation circuit for a bandgap voltage reference source

Abstract

The high-order nonlinear compensation circuit for the bandgap voltage reference source disclosed by the present invention includes a current generation circuit, a high-order nonlinear compensation circuit, and an output circuit; the current generation circuit has N current generation branches; the high-order nonlinear compensation circuit is an N-order nonlinear generation circuit, and the input end of the N-order nonlinear generation circuit is connected to the N current generation branches in one-to-one correspondence, and based on the currents with different temperature coefficients output by the N current generation branches, an N-order temperature compensation current with a positive temperature coefficient is generated; the output circuit generates an N-order compensation voltage based on the N-order temperature compensation current, and after superimposing it with the first-order bandgap reference voltage, a reference voltage is generated. The present invention can independently compensate the second-order and higher-order nonlinear components of the bandgap voltage reference, and the temperature drift of the reference source after compensation is less than 1 ppm / °C.

Description

Technical Field

[0001] The present invention relates to the technical field of bandgap voltage references, and more particularly to a high-order nonlinear compensation circuit for a bandgap voltage reference. Background Art

[0002] A bandgap voltage reference can provide a reference voltage with a low temperature coefficient and is thus widely used in various integrated circuit products. Its basic principle is to generate a voltage with a positive temperature coefficient to offset the negative temperature coefficient of the base-emitter voltage (Vbe) of a triode. The negative temperature coefficient of Vbe includes a first-order linear component, second-order, third-order, and higher-order nonlinear components. After the first-order linear component of Vbe is offset, the remaining second-order and higher-order nonlinear components may cause the temperature drift of the reference source to exceed 10 ppm / °C. For some applications, such as providing a voltage reference source for a high-precision ADC, the temperature drift needs to be less than 2 ppm / °C, or even 1 ppm / °C. In this case, it is necessary to offset the second-order, third-order, and even higher-order nonlinear components of the negative temperature coefficient of Vbe. Summary of the Invention

[0003] Object of the Invention: The object of the present invention is to provide a high-order nonlinear compensation circuit for a bandgap voltage reference, which can independently compensate the second-order and higher-order nonlinear components of the bandgap voltage reference, and the temperature drift of the reference source after compensation is less than 1 ppm / °C, aiming at the deficiencies of the prior art.

[0004] Technical Solution: The high-order nonlinear compensation circuit for a bandgap voltage reference according to the present invention includes a current generation circuit, a high-order nonlinear compensation circuit, and an output circuit; the current generation circuit has N current generation branches; the high-order nonlinear compensation circuit is an N-order nonlinear generation circuit, and the input end of the N-order nonlinear generation circuit is connected to the N current generation branches one by one, and based on the currents with different temperature coefficients output by the N current generation branches, an N-order temperature compensation current with a positive temperature coefficient is generated; the output circuit generates an N-order compensation voltage based on the N-order temperature compensation current, and superimposes it with the first-order bandgap reference voltage to generate a reference voltage.

[0005] To further improve the above technical solution, the current generation circuit has 2 current generation branches, and based on the currents with different temperature coefficients output by the 2 current generation branches, the high-order nonlinear compensation circuit generates a second-order temperature compensation current with a positive temperature coefficient; or the current generation circuit has 3 current generation branches, and based on the currents with different temperature coefficients output by the 3 current generation branches, the high-order nonlinear compensation circuit generates a part or all of the third-order temperature compensation current with a positive temperature coefficient.

[0006] Further, the high-order nonlinear compensation circuit includes an input-side connection branch and an output-side connection branch. The input-side connection branch includes N triodes, the base and collector of each triode are interconnected, the N triodes are sequentially connected in series with the emitter of the previous triode and the collector of the next triode, and the bases of the N triodes are connected to the output ends of the N current generation branches in a one-to-one correspondence; the output-side connection branch includes N - 1 triodes and an output triode, where the N - 1 triodes are symmetrically arranged with the triodes of the input-side connection branch, and after the N - 1 triodes are sequentially connected in series, a constant current Iext is connected, and the node between the triode and the constant current Iext is connected to the base of the output triode.

[0007] Further, the current generation branch uses a current source or a current well and the parameter selection matches the target nonlinear polynomial coefficient, and the triode uses an NPN or corresponding PNP transistor.

[0008] Further, the current generation branch includes a constant current Iext and a linear current PTAT with a positive temperature coefficient, and the node between Iext and PTAT is connected to the base of the triode.

[0009] Further, the current generation circuit includes a first current generation branch and a second current generation branch. The high-order nonlinear compensation circuit includes triodes Q0, Q1, Q2, Q3. The bases and collectors of triodes Q3 and Q1 are interconnected, the emitter of triode Q3 is connected to the collector of triode Q1. The output end of the first current generation branch is connected to the base of triode Q3 and the current flowing through triode Q3 is Q3(T) = k1*Iext - Iptat(T). The output end of the second current generation branch is connected to the base of triode Q1 and the current flowing through triode Q1 is IQ1(T) = Iptat(T) - k2*Iext, and k1*I ext = I ptat (T2), k2*I ext = I ptat (T0), T2 > T0; Triode Q3 is connected to the base of triode Q2, the emitter of triode Q2 is connected to the constant current Iext and the connection node is connected to the base of triode Q0. By such setting, a second-order nonlinear current circuit can be generated to generate a second-order nonlinear component within the required temperature range.

[0010] Further, the current generation circuit includes a first current generation branch, a second current generation branch, and a third current generation branch. The high-order nonlinear compensation circuit includes transistors Q0, Q1, Q2, Q3, Q4, and Q5. The bases and collectors of transistors Q5, Q3, and Q1 are interconnected. The emitter of transistor Q5 is connected to the collector of transistor Q3, and the emitter of transistor Q3 is connected to the collector of transistor Q1. The output terminal of the first current generation branch is connected to the base of transistor Q5, and the current flowing through transistor Q5, IQ5(T) = k3*Iext - Iptat(T). The output terminal of the second current generation branch is connected to the base of transistor Q3, and the current flowing through transistor Q3, IQ3(T) = k2*Iext - Iptat(T). The output terminal of the third current generation branch is connected to the base of transistor Q1, and the current flowing through transistor Q1, IQ1(T) = Iptat(T) - k1*Iext, where k1*I ext = I ptat (T0), k2*I ext = I ptat (T1), k3*I ext = I ptat (T2), T2 > T1 > T0; The base of transistor Q5 is connected to the base of transistor Q4. The emitter of transistor Q4 is connected to the collector of transistor Q2, and the base and collector of transistor Q2 are interconnected. The emitter of transistor Q2 is connected to the constant current Iext, and the connection node is connected to the base of transistor Q0. By such an arrangement, a third-order nonlinear current circuit is generated, and the corresponding current waveform is the upper half of the third-order nonlinear component waveform to generate the third-order nonlinear component within the required temperature range for partial compensation.

[0011] Further, the current generation circuit includes a first current generation branch, a second current generation branch, and a third current generation branch. The high-order nonlinear compensation circuit includes transistors Q0, Q1, Q2, Q3, Q4, Q5, Q6, and Q7. The bases and collectors of transistors Q5, Q3, and Q1 are interconnected. The emitter of transistor Q5 is connected to the collector of transistor Q3, and the emitter of transistor Q3 is connected to the collector of transistor Q1. The output terminal of the first current generation branch is connected to the base of transistor Q5, and the current flowing through transistor Q5, IQ5(T) = k3*Iext - Iptat(T). The output terminal of the second current generation branch is connected to the base of transistor Q3, and the current flowing through transistor Q3, IQ3(T) = Iptat(T) - k2*Iext. The output terminal of the third current generation branch is connected to the base of transistor Q1, and the current flowing through transistor Q1, IQ1(T) = Iptat(T) - k1*Iext. The transistor Q5 is connected to the base of transistor Q4. The emitter of transistor Q4 is connected to the collector of transistor Q2, and the base and collector of transistor Q2 are interconnected. The emitter of transistor Q2 is connected to the constant current Iext, and the connection node is connected to the base of transistor Q6. Transistors Q6 and Q7 are symmetrically arranged, and transistors Q0 and Q7 are symmetrically arranged. By such an arrangement, a third-order nonlinear current circuit is generated, and the corresponding current waveform is the lower half of the third-order nonlinear component waveform to generate a part of the third-order nonlinear component within the required temperature range.

[0012] Combine the output terminal of the current circuit that generates the upper half of the third-order nonlinear component waveform with the output terminal of the current circuit that generates the lower half of the third-order nonlinear component waveform to generate a complete third-order nonlinear current waveform.

[0013] Beneficial effects: Compared with the prior art, the advantages of the present invention are as follows: The high-order nonlinear compensation circuit of the bandgap voltage reference source provided by the present invention generates second-order or higher-order linear components within the required range by selecting current sources with different temperature coefficients to independently compensate the second-order and higher-order nonlinear components of the bandgap voltage reference. After compensation, the temperature drift of the reference source can be less than 1 ppm / °C. Description of the Drawings

[0014] FIG. 1(a) is a schematic circuit diagram of a conventional bandgap voltage reference with high-order temperature coefficient compensation;

[0015] FIG. 1(b) is a schematic diagram of the second-order and third-order nonlinear components of the Vbe of the transistor in the circuit shown in FIG. 1(a) changing with temperature;

[0016] Figure 2 is a schematic diagram of the Nth-order nonlinear generation circuit implemented by connecting N transistors in series proposed by the present invention;

[0017] Fig. 3(a) is a schematic diagram of the second-order nonlinear current generation circuit that varies with temperature proposed by the present invention;

[0018] Fig. 3(b) is a schematic diagram of the output current characteristics of the circuit shown in Fig. 3(a);

[0019] Fig. 4(a) is a schematic diagram of the third-order compensation low-temperature part generation circuit that varies with temperature proposed by the present invention;

[0020] Fig. 4(b) is a schematic diagram of the output current waveform of the circuit shown in Fig. 4(a);

[0021] Fig. 4(c) is a schematic diagram of the third-order compensation high-temperature part generation circuit that varies with temperature proposed by the present invention;

[0022] Fig. 4(d) is a schematic diagram of the output current waveform of the circuit shown in Fig. 4(c);

[0023] Fig. 5(a) is the curve of the output varying with temperature after the first-order temperature coefficient of the bandgap voltage reference source provided by the present invention is eliminated;

[0024] Fig. 5(b) is the curve of the output varying with temperature after the first-order and second-order temperature coefficients of the bandgap voltage reference source provided by the present invention are eliminated;

[0025] Fig. 5(c) is the curve of the output varying with temperature after the first-order, second-order temperature coefficients and the third-order temperature coefficient of the low-temperature part of the bandgap voltage reference source provided by the present invention are eliminated;

[0026] Fig. 5(d) is the curve of the output varying with temperature after the first-order, second-order and all third-order temperature coefficients of the bandgap voltage reference source provided by the present invention are eliminated. Detailed implementation manners

[0027] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings, but the protection scope of the present invention is not limited to the described embodiments.

[0028] Embodiment 1: Fig. 1(a) shows a traditional bandgap voltage reference source with high-order temperature coefficient compensation, where Vbg is the reference voltage output, transistors Q1 and Q2 provide the Vbe voltage, resistors R3 and R4 generate a voltage with a positive temperature coefficient to compensate for the negative temperature coefficient voltage of Vbe, Icomp(T) is used to compensate for the high-order nonlinear component of Vbe, and the operational amplifier OP, resistors R1 and R2 feedback network (usually R1 = R2, Q2 = N * Q1) generates a proportional current for Q1 and Q2.

[0029] The output voltage Vbg of the bandgap voltage reference source:

[0030]

[0031] The second-order and third-order non-linear components of Vbe varying with temperature T are shown in Fig. 1(b), where X(T) is the second-order component, Y(T) is the third-order component, and T0 / T1 / T2 are three temperature points. For example, T0 = -40°C, T1 = 50°C, T2 = 125°C, and X(T0) = X(T2) = Y(T0) = Y(T1) = Y(T2) = 0.

[0032] The high-order non-linear compensation circuit of the bandgap voltage reference source provided by the present invention, as Figure 2 shown, uses N npn transistors connected in series to implement an N-order non-linear generation circuit, where Ip1 to IpN can be current sources or current sinks, Figure 2 and can also be correspondingly changed to a circuit using pnp.

[0033] Among them, Figure 2 the output Iout of is:

[0034]

[0035] It can be seen from formula (2) that by selecting currents with different temperature coefficients, high-order non-linear currents above the second order can be generated, and arbitrary high-order non-linear compensation currents or voltages can be generated to compensate for the second-order and third-order non-linear components including those in Fig. 1(b).

[0036] Embodiment 2: Fig. 3(a) is a simplified embodiment of a circuit for generating a second-order non-linear current, which can generate second-order non-linear components within a certain temperature range. Among them, Iext is a constant current that does not change with temperature T, and Iptat(T) is a linear current that is proportional to temperature T. The currents flowing through Q1 to Q3 are respectively IQ1(T) = Iptat(T) - k2 * Iext, IQ2(T) = k3 * Iext; IQ3(T) = k1 * Iext - Iptat(T), and the specific values of IQ1(T) to IQ3(T) need to be matched with the target non-linear polynomial coefficients.

[0037] Output current Iout:

[0038]

[0039] Formula (3) selects k1 * I ext = I ptat (T2), k2 * I ext [[ID=�6]]= I ptat (T0), T2 > T0. Since Q1 and Q3 can only conduct unidirectionally, so T0 ≤ T ≤ T2, Iout has a current output, and Iout = 0 in other temperature ranges, and the waveform current shown in Fig. 3(b) can be obtained.

[0040] Embodiment 3: Figure 4(a) is a simplified embodiment of a circuit for generating a third-order nonlinear current, which can generate a third-order nonlinear component within a certain temperature range. The currents of Q1, Q3, and Q5 are respectively IQ1(T) = Iptat(T) - k1*Iext, IQ3(T) = k2*Iext - Iptat(T), IQ5(T) = k3*Iext - Iptat(T); the currents of Q2 and Q4 are: IQ2(T) = IQ4(T) = k0*Iext.

[0041] Output current Iout:

[0042]

[0043] Formula (4) selects k1*I ext = I ptat (T0), k2*I ext = I ptat (T1), k3*I ext = I ptat (t2), T2 > T1 > T0. Since Q1, Q3, and Q5 can only conduct unidirectionally, so T0 ≤ T ≤ T1, Iout has a current output, and for other temperature ranges, Iout = 0. The current waveform shown in Figure 4(b) can be obtained. Similarly, the current waveform shown in Figure 4(d) can be obtained from Figure 4(c). By combining the circuits in Figures 4(a) and (c) and connecting the outputs together, a complete third-order nonlinear current waveform can be obtained to compensate for Y(T) in Figure 1(b).

[0044] Figure 5 shows the simulation results based on the circuits shown in Figures 3 to 4. Among them, Figure 5(a) is the reference voltage output that eliminates the first-order linear component varying with temperature, which varies by 2.0 mV within the range of -40°C to 125°C, corresponding to 10.0 ppm / °C. After using the second-order nonlinear compensation circuit in Figure 3(a), the reference voltage output is as shown in Figure 5(b), which varies by 0.45 mV within the same temperature range, corresponding to 2.2 ppm / °C, and the voltage outside the range of -40°C to 125°C basically does not change. After using the third-order nonlinear compensation circuit in Figure 4(a), the reference voltage output is as shown in Figure 5(c). This circuit only compensates for the third-order nonlinearity within the range of -40°C to 50°C, and the voltage output outside the range remains unchanged. The voltage change within the range of -40°C to 50°C is reduced from 0.327 mV to 0.063 mV. After using the third-order nonlinear compensation circuit in Figure 4(c), the reference voltage output is as shown in Figure 5(d). This circuit only compensates for the third-order nonlinearity within the range of 50°C to 125°C, and the voltage output outside the range remains unchanged. The voltage change within the range of 50°C to 125°C is reduced from 0.182 mV to 0.075 mV, and the change within the entire range of -40°C to 125°C is 0.122 mV, corresponding to 0.6 ppm / °C.

[0045] As described above, although the present invention has been shown and described with reference to particular preferred embodiments, it should not be construed as a limitation on the invention itself. Various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A high-order nonlinear compensation circuit for a bandgap voltage reference source, comprising a current generation circuit, a high-order nonlinear compensation circuit, and an output circuit; The current generating circuit has N current generating branches; the high-order nonlinear compensation circuit is an N-order nonlinear generating circuit, and the input end of the N-order nonlinear generating circuit is connected to the N current generating branches in one-to-one correspondence. Based on the currents with different temperature coefficients output by the N current generating branches, an N-order temperature compensation current with a positive temperature coefficient is generated; the output circuit generates an N-order compensation voltage based on the N-order temperature compensation current, and generates a reference voltage after superimposing it with the first-order bandgap reference voltage; The current generating circuit has two current generating branches. Based on the currents with different temperature coefficients output by the two current generating branches, the high-order nonlinear compensation circuit generates a second-order temperature compensation current with a positive temperature coefficient; Or the current generating circuit has three current generating branches. Based on the currents with different temperature coefficients output by the three current generating branches, the high-order nonlinear compensation circuit generates some or all of the third-order temperature compensation currents with a positive temperature coefficient; It is characterized in that: the high-order nonlinear compensation circuit includes an input-side connection branch and an output-side connection branch. The input-side connection branch includes N triodes, the base and collector of each triode are interconnected, and between the N triodes, the emitter of the previous triode and the collector of the next triode are sequentially connected in series. The bases of the N triodes are connected to the output ends of the N current generation branches in one-to-one correspondence; the output-side connection branch includes N - 1 triodes and an output triode. The base of the first triode in the output-side connection branch is connected to the base of the first triode in the input-side connection branch, and after the N - 1 triodes are sequentially connected in series, a constant current I ext is connected. The node between the triode and the constant current I ext is connected to the base of the output triode. The current generation branch uses a current source or a current well, and the selection of parameters matches the coefficients of the target nonlinear polynomial. The triode uses an NPN or corresponding PNP transistor; the current generation branch includes a constant current I ext and a linear current I ptat (T) with a positive temperature coefficient. The node between I ext and I ptat (T) is connected to the base of the triode.

2. The high-order nonlinear compensation circuit for the bandgap voltage reference source according to claim 1, characterized in that: The current generation circuit includes a first current generation branch and a second current generation branch. The high-order nonlinear compensation circuit includes transistors Q0, Q1, Q2, and Q3. The bases and collectors of transistors Q3 and Q1 are interconnected. The emitter of transistor Q3 is connected to the collector of transistor Q1. The output terminal of the first current generation branch is connected to the base of transistor Q3, and the current flowing through transistor Q3 is IQ3(T) = k1*I ext -I ptat (T). The output terminal of the second current generation branch is connected to the base of transistor Q1, and the current flowing through transistor Q1 is IQ1(T) = I ptat (T) - k2*I ext , and ; the transistor Q3 is connected to the base of transistor Q2. The emitter of transistor Q2 is connected to a constant current Iext, and the connection node is connected to the base of transistor Q0.

3. The high-order nonlinear compensation circuit for the bandgap voltage reference source according to claim 1, wherein: The current generation circuit includes a first current generation branch, a second current generation branch, and a third current generation branch. The high-order nonlinear compensation circuit includes transistors Q0, Q1, Q2, Q3, Q4, and Q5. The bases and collectors of transistors Q5, Q3, and Q1 are interconnected. The emitter of transistor Q5 is connected to the collector of transistor Q3, and the emitter of transistor Q3 is connected to the collector of transistor Q1. The output terminal of the first current generation branch is connected to the base of transistor Q5, and the current flowing through transistor Q5 is IQ5(T) = k3*I ext -I ptat (T). The output terminal of the second current generation branch is connected to the base of transistor Q3, and the current flowing through transistor Q3 is IQ3(T) = k2*I ext -I ptat (T). The output terminal of the third current generation branch is connected to the base of transistor Q1, and the current flowing through transistor Q1 is IQ1(T) = I ptat (T) - k1*I ext ; ; The transistor Q5 is connected to the base of transistor Q4. The emitter of transistor Q4 is connected to the collector of transistor Q2, and the base and collector of transistor Q2 are interconnected. The emitter of transistor Q2 is connected to the constant current I ext and the connection node is connected to the base of transistor Q0.

4. The high-order nonlinear compensation circuit for the bandgap voltage reference source according to claim 1, wherein: The current generation circuit includes a first current generation branch, a second current generation branch, and a third current generation branch. The high-order nonlinear compensation circuit includes transistors Q0, Q1, Q2, Q3, Q4, Q5, Q6, and Q7. The bases and collectors of transistors Q5, Q3, and Q1 are interconnected. The emitter of transistor Q5 is connected to the collector of transistor Q3, and the emitter of transistor Q3 is connected to the collector of transistor Q1. The output terminal of the first current generation branch is connected to the base of transistor Q5, and the current IQ5(T) flowing through transistor Q5 is IQ5(T) = k3*I ext -I ptat (T). The output terminal of the second current generation branch is connected to the base of transistor Q3, and the current IQ3(T) flowing through transistor Q3 is IQ3(T) = I ptat (T) - k2*I ext . The output terminal of the third current generation branch is connected to the base of transistor Q1, and the current IQ1(T) flowing through transistor Q1 is IQ1(T) = I ptat (T) - k1*I ext ; The transistor Q5 is connected to the base of transistor Q4. The emitter of transistor Q4 is connected to the collector of transistor Q2, and the base and collector of transistor Q2 are interconnected. The emitter of transistor Q2 is connected to the constant current I ext and the connection node is connected to the base of transistor Q6. Transistors Q6 and Q7 are connected in series, and transistors Q0 and Q7 are mirror - configured.

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